HANGZHOU, China (Reuters) - U.S. President Barack Obama said on Monday that U.S. trading partners in Asia did not need to be persuaded of the benefits of the Trans-Pacific Partnership, just that Washington would eventually approve the trade pact.

Obama has made the 12-nation TPP the centerpiece of a diplomatic "pivot" to Asia, but the prospects for U.S. congressional approval have looked increasingly dim, with both major presidential candidates - Democrat Hillary Clinton and Republican Donald Trump - standing opposed.

Administration officials had said that Obama would make the case for the TPP during his visit to Asia, including in a speech he has scheduled in Laos on Tuesday.

"I don't have to sell it to Asian leaders here who were part of the negotiations because they see this as the right thing to do for their own countries," Obama told reporters at the close of the G20 summit in the eastern Chinese city of Hangzhou.

"And what I'll be telling them is that the U.S. has never had a smooth, uncontroversial path to ratifying trade deals, but they eventually get done," Obama said.

"Back home we'll have to cut through the noise once election season is over. It's always a little noisy there," he said.

The White House has said it could still win congressional approval of the trade pact before Obama leaves office, and warned that failing to do so would undermine U.S. leadership in the region and allow China to increasingly set the terms of world trade.